| Recently, with the development of economy, the possession of central air-conditioning system is larger than before. The central air-conditioning system is regarded as the biggest energy-consumption single equipment in the large scale public building. The electricity consumption of such system accounts for more than half consumption in the whole building, which has been one of the most important aspects in China's energy-saving and environmental protection. In the field of refrigeration and air-conditioning, the further generalization of cool-storage air-conditioning technology is one of the effective measures in solving both electrical-tension in peak period and electrical-surplus in off-peak period. At present the ice-ball cool storage system is more widely applied. The water freezing point is low, which make the evaporation temperature,COP and cool capacity of cool-storage air-conditioning is great lower than conventional air condition system. In addition, the system is made more complex by the double-stage mode refrigeration main machine applied in the air-conditioning mode and ice storage mode. Therefore, this paper presents that the technology of phase-change cool storage is applied in conventional central air-conditioning system, then develops PCM which is adapt to the conventional air-conditioning mode, adds PCM to cool storage in the process of conventional air-conditioning system. The goal of shift electrical energy demand from peak can be realized by storing coldness in off-peak period and discharging coldness in peak period.The preparation,thermal properties of PCM and dynamic characteristic of cool storage and cool discharge courses of PCM cool storage system is systematically studied. The major research efforts are indicated from the following aspects:(1) A new organic PCM HS-1 (base liquid) used in central air-conditioning system was developed. The further research of using nanocomposite technology to the organic PCM HS-1 was made according to low thermal conductivity of organic PCM. A preparation method of homogeneous stable nanocomposites cool storage material was made by directly mixing HS-1 with nano-TiO2 and nano-Cu individually and adding dispersant,supersonic surging. The dispersants were confirmed by the method of Zeta Potentiometric Analysis. The influence of dispersant on dispersion, time of supersonic on dispersion, consistence of dispersant in the best supersonic time and additive of nano and non-nano on the dispersion were deeply researched. The best condition of preparation of TiO2/HS-1 and Cu/HS-1 were confirmed at last. Dispersion mechanism of nano-composites organic PCM are explained by DLVO theory and interspace stabilization theory.(2) Latent heat and phase change temperature and specific heat of nanocomposites HS-2 were measured by Differential Scanning Calorimetry (DSC). The value of latent heat is 146.56kJ/kg, solidification temperature is 7.4℃, melting temperature is 8.5℃. After fifty times freezing/melting cycles, the latent heat and phase transition temperature of nano-composites still remain constant, which showing good dispersion and no off-phase. Thermal conductivity of PCM is measured by non-stable method. The thermal conductivity of HS-2 is more than 17.7% than HS-1.(3) The solidification problem in the cool storage sphere was researched according to the developed organic nano-composites cool storage PCM. The model of solidification problem of PCM cool storage sphere was established and results was obtained by enthalpy method. In order to validate the results, the solidification course of HS-2 was researched by small cool-storage test-bed established by us. The rule of phase interface and distribution of temperature in the cool storage sphere generated from experiment are consistent with the results of theory, showing that the validity of the theory.(4) Characteristics of cool storage sphere melting were researched. Model of melting problem was established according to the density difference between solid and liquid and solid state ascending. The courses of melting were computer simulated by the apparent heat volume method. The influence of solid state ascending and radius of cool storage sphere on melting are researched and validated by the experiment, which offer theory evidence and data for the application of cool storage technology.(5) Dynamic simulation and experimental research of cool charge and discharge were made. PCM store model was established, which the model is consist of coolant and cool-storage ball and two parts is blocked off by the shell of ball. Namely, the whole store is divided by several parts along with the direction of length assumed that the temperature of coolant is evenly in each part and temperature of each point is regarded as the function of space. Apparent heat volume was adopted to simulate store model, the influence of coolant flux and inlet temperature and the rule of freezing and melting can be obtained. Small cool-storage system equipment was designed and established by us and some related experiments were carried out on it. The validated results and reasons of difference between theory and practice can be obtained by such experiment.The nano-composites PCM of conventional air-conditioning can be obtained by this paper. All of this can make the design and project of PCM stores more rationalized and offer theory evidence and data for the application of cool storage technology, which has the guiding role for the further product forming.
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